1. Field of the Invention
The present invention relates to a calibration method and a corresponding apparatus for optical imaging lens system with double optical paths, and more particularly, to a calibration method for optical imaging lens system with double optical paths which is able to calibrate images coming from different optical systems.
2. Description of the Prior Art
Calibration of cameras, especially the calibration of distortion, has been considered as an important issue in aerial photographic measurement and machine vision system (MVS). The article entitled “Camera Calibration with Distortion Models and Accuracy Evaluation” (Juyan Weng, IEEE TRANSACTION ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE VOL. 14 NO. 10 Oct. 1992) proposes a number of methods for calibrating distortions. However, as cameras are widely used, commercially and industrially, it will be insufficient to simply calibrate the distortions. Improving uniformity in images generated by different cameras is also required. Therefore, there is a demand for a method which is able to correct image non-uniformity caused by differences among various components produced in massive quantities.
As an optical system comprises a number of precise optical components, one optical system will be different from anther in optical parameters, such as lateral magnification, contrast, image surface illumination and distortion, due to the subtle differences in the size of the individual components thereof. The characteristics of different batches of sensors vary slightly as well. Non-uniform images displayed continuously at a high speed will cause much discomfort for the average viewers.
Therefore, a need exists in the art for a method which can effectively calibrate non-uniformity in images generated by different optical lenses.